Novel polymerization catalyst and process for using same to polymerize olefins

ABSTRACT

There is provided a solid, particulate, catalytic complex suitable for the stereospecific polymerization of olefins prepared by reducing TiCl 4 , contacting the resultant reduced solid with a complexing agent to obtain a treated solid and contacting the treated solid with TiCl 4  in the presence of silica which has been treated with an aromatic ester. When such a catalyst complex is combined with a suitable activator to polymerize olefins, a high degree of stereospecificity is attained, the activity of the catalyst complex is reduced for polymerization control and the efficiency of the titanium employed is enhanced.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a division of application Ser. No. 227,733 filed Jan. 23, 1981,now U.S. Pat. No. 4,367,161.

Reference is made to applicants' following U.S. application:

U.S. patent application Ser. No. 227,691, filed Jan. 23, 1981, entitled"Polymerizing Olefins With a Novel Catalyst".

The disclosure of the foregoing application is hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention relates to a novel catalyst composition which isuseful in the stereospecific polymerization of olefins. This inventionalso relates to a process for using such a catalyst composition topolymerize olefins.

DESCRIPTION OF THE PRIOR ART

It is well known in the art to use metallic catalysts to polymerizeolefins such as ethylene, propylene, 1-butene and the like to formpolymers of high molecular weight. One such general class of metalliccatalyst are the "Ziegler-Natta" types consisting of aluminum alkyls oralkyl halides and titanium halides. Such catalysts polymerize olefins ina stereospecific manner resulting in the formation of olefin polymerswhich are characterized by high degrees of isotacticity andcrystallinity.

British Pat. No. 1,391,067 to Hermans et al, the disclosure of which isincorporated herein by reference, discloses the preparation of a solid,particulate catalytic complex for the stereospecific polymerization ofolefins. The catalytic complex is prepared by reducing TiCl₄ to obtainTiCl₃, treating the TiCl₃ with a complexing agent and then contactingthe treated TiCl₃ with liquid TiCl₄. The resultant catalyst complex incombination with a suitable activator, such as an organo compound ofaluminum, is used to polymerize olefins to obtain highly crystallinepolymers. However, the activity of the catalyst complex is so high as tocause problems during polymerization, e.g., very rapid localpolymerization at the point where the catalyst is fed to thepolymerization reactor. This can lead to fouling problems in the reactoror the production of non-uniform products.

British Pat. No. 2,010,870 A to Hyde discloses that alpha olefins can bepolymerized by contacting them under polymerization conditions using acatalyst component comprising a transition metal compound, for example,TiCl₄, and a co-catalyst component, for example triethylaluminum. Ratherthan use TiCl₄ alone in such combination, it can be prereacted with asupport material. When TiCl₄ is so supported, the resultant catalyst hasa very high activity and can cause polymerization problems. The claimedinvention resides in admixing silica with the catalyst combination. Thepresence of silica in the catalyst system reduces the activity of thecatalyst moderating the polymerization reaction where it is used andalso results in a more efficient use of the titanium employed.

SUMMARY OF THE INVENTION

It has now been found that a solid, particulate, catalytic complexsuitable for the stereospecific polymerization of olefins can beprepared by reducing TiCl₄, contacting the resultant reduced solid witha complexing agent to obtain a treated solid and contacting the treatedsolid with TiCl₄ in the presence of silica which has been treated withan aromatic ester. When such a catalyst complex is combined with asuitable activator to polymerize olefins, a high degree ofstereospecificity is attained. The activity of the catalyst complex isreduced for polymerization control as compared to the activated catalystcomplex disclosed in British Pat. No. 1,391,067. However, by using thetreated silica, the amount of polymer formed per amount of titaniumemployed is increased. If the silica used in the preparation of thecatalyst complex of this invention is not pretreated with an aromaticester, it acts to deactivate some of the active polymerization sites.

The aromatic ester used to treat the silica can be selected from thosedefined by the following formulas: ##STR1## wherein Y is an alkyl grouphaving from about one to about eight carbon atoms, preferably from aboutone to about two carbon atoms, or an alkenyl group having from about twoto about eight carbon atoms, preferably from about two to about threecarbon atoms; each X can be hydrogen, a halogen, particularly chlorine,an alkoxy group having from about one to about eight carbon atoms,preferably from about one to about two carbon atoms or it can be one ofthe groups previously defined for Y; and x can be an integer from one totwo, preferably one. When x is two and the aromatic ester has two orthree fused rings, the ester groups may be substituted on the same ordifferent rings. It will be understood that when the aromatic ester hastwo or three fused rings, the X groups are present on all of the rings.

The silica employed herein is suitably any silica having a mean particlesize in the range of about 1 to about 100 microns, preferably from about1 to about 25 microns.

In treating the silica herein with the aromatic ester, the molar ratiosof aromatic ester to silica can be in the range of about 1:10 to about1:1, preferably about 1:8 to about 1:2.

To assure that the silica is free of water prior to being treated withthe aromatic ester, it is preferred that it be calcined in any suitableatomosphere, for example, air, nitrogen or hydrogen, at a temperature inthe range of about 350° to about 700° C., preferably about 400° to about500° C., for about one to about five hours, preferably about two tothree hours, at a pressure that can be as high as about 500 pounds persquare inch gauge (3450 kPa), but preferably is atmospheric.

Treatment of the silica with the aromatic ester can be effected byintroducing them into a hydrocarbon solvent, such as hexane, heptane andcyclohexane, and, while stirring, heating the resulting slurry in atemperature range of about 70° to about 300° C., preferably about 100°to about 200° C., for about one to about ten hours, preferably about twoto about five hours, at a pressure which can be as high as about 500pounds per square inch gauge (3450 kPa), but preferably aboutatmospheric. The treated silica can be washed with a suitablehydrocarbon solvent, for example, such as defined above, filtered anddried in a vacuum to remove solvent therefrom.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In preparing the catalyst complex, TiCl₄ is reduced to a solid productbased on TiCl₃ (referred to herein as "reduced solid") as described inBritish Pat. No. 1,391,067. This is accomplished by means of treatmentwith a reducing agent of the general formula AlR_(n) X_(3-n), in which Rcan be a hydrocarbon radical containing from 1 to 18 carbon atoms,preferably from 1 to 12 carbon atoms, e.g., R can be an alkyl, aryl,arylalkyl, alkylaryl, or cycloalkyl radical containing from 2 to 6carbon atoms; X is a halogen, e.g., fluorine, chlorine, bromine, oriodine, preferably chlorine; n is any number greater than 0 but nogreater than 3, preferably not less than 1.5 nor greater than 2.5, thebest results being obtained when n is equal to 2.

Suitable reducing agents which may also be used include organoaluminumpolymers obtained by reacting a trialkylaluminum, in which the alkylradicals may contain from 1 to 18 carbon atoms, with a diolefincontaining from 4 to 18 carbon atoms; more particularly, therefore, usemay be made of the compounds known as isoprenylaluminums. These reducingagents are similar for the present purpose to those of the formula AlR₃.

The free-flowing characteristics of the reduced solid obtained in thismanner are excellent, and its apparent density is very high (from 0.8 to1.3 kg/dm³).

In order to obtain this reduced solid having good morphology, it ispreferred for the reduction to be carried out under mild conditions,with slight agitation, at a temperature between -100° and 30° C.,preferably between -50° and 20° C. Particularly good results areobtained when the reduction is carried out at 0±2° C. It is advantageousfor the reaction to be performed in an anert diluent, which can be anyof those commonly used in the polymerization of olefins, and preferablycomprises one or more aliphatic or cycloaliphatic hydrocarbonscontaining from 5 to 12 carbon atoms. The diluent most conveniently usedin hexane. This type of diluent can be used throughout the preparationof the catalytic complex.

A convenient procedure consists in dissolving the TiCl₄ in the inertdiluent in a proportion of 100 to 400 ml. of TiCl₄, preferably 200 to300 ml. of TiCl₄, per liter of diluent and progressively adding thereducing agent, dissolved in a diluent in a proportion of 250 to 500 g.,preferably 350 to 425 g., of reducing agent per liter of diluent. Theaddition of the reducing agent is preferably spread out over a longperiod, for example, more than 1 hour and preferably more than 3 hours.The proportion of reducing agent used is suitably about one mole permole of TiCl₄. Nevertheless, a slight excess of reducing agent (forexample up to 25%) does not impair the formation of a reduced solidhaving a good morphology.

Another procedure which may be followed consists in preparing a solutionof TiCl₄ and the reducing agent at a very low temperature (for example,between -100° and -50° C.) and allowing the temperature to rise veryslowly to ambient temperature, for example, over a period of 6 hours.

After the reagents have been brought together, the temperature of thereaction mixture can be progressively raised to between 20° and 120° C.,preferably between 40° and 100° C., under continuous moderate agitation.Heat treatment can then be effected at a moderate temperature, thistemperature being maintained throughout the period of the heattreatment, which is advantageously over 15 minutes. The higher thetemperature at which the heat treatment is effected, the shorter thetime required for this treatment will generally be. The reduced solidthus prepared can optionally be separated from the reaction medium byany applicable method, and then washed with diluent.

The reduced solid obtained is not composed exclusively of TiCl₃, but isa TiCl₃ -based composition containing aluminum compounds which containhalogen and/or hydrocarbon radicals. Preferably the composition containsmore than 0.3 molecule of aluminum compound(s) per molecule of TiCl₃.

In this reduced solid, the TiCl₃ is essentially in the beta crystallineform. The specific surface area of this reduced solid is low (about 1 m²/g), and its catalytic properties are not good. More particularly, itsstereospecificity and its activity are poor.

The reduced solid thus prepared is next treated as described in BritishPat. No. 1,391,067 with a complexing agent, this being a compoundcapable of forming complexes with titanium chloride, aluminum halides,and aluminum organohalides. It is preferred to use an organic compoundcontaining one or more donor atoms or groups having one or more pairs offreely available electrons capable of effecting coordination withtitanium and aluminum and containing from 1 to 30 carbon atoms perelectron donor atom or group.

Among the atoms capable of donating one or more pairs of electrons arethe atoms of non-metals of Groups V and VI of the PeriodicClassification, for example, oxygen, sulfur, nitrogen, phosphorus,antimony and arsenic.

As examples of organic compounds containing groups capable of donatingone or more pairs of electrons mention may be made of ethers,thioethers, thiols, phosphines, stibines, arsines, amines, amides,ketones and esters.

It is preferred to use complexing agents of the general formulaR'--O--R", R'--S--R", R'--N--R" or R'--S--H, in which R' and R" are eacha hydrocarbon radical containing from 1 to 15 carbon atoms, andpreferably an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl radical.R' and R" can be the same or different. Particularly good results areobtained when R' and R" are unbranched or branched aliphatic radicals,are identical, and contain from 2 to 8 carbon atoms, preferably from 4to 6 carbon atoms.

The treatment of the reduced solid with the complexing agent (to formwhat is herein referred to as the "treated solid" ) is advantageouslyeffected in the presence of the diluent used in the reduction of theTiCl₄, assuming that one is used and the reduced solid is not separated.The reduced solid can be kept in suspension by agitation. If preferred,however, a fresh diluent can be used instead. The proportion of diluentis preferably such that the content of reduced solid therein isequivalent to between 0.03 and 4 moles of TiCl₃ (i.e., TiCl₃ present inthe reducing solid) per liter of diluent, e.g., equivalent to between0.3 and 2 moles of TiCl₃ per liter of diluent. The temperature duringthe treatment with the complexing agent is not critical, but it ispreferred to operate at a temperature between 0° and 80° C. The periodof the treatment with the complexing agent is also not critical, but aperiod longer than 5 minutes is preferable.

The proportion of complexing agent used is preferably between 0.1 and2.5 moles, e.g., between 0.5 and 1.75 moles, per mole of TiCl₃ presentin the reduced solids. Particularly good results are obtained when aproportion of complexing agent between 0.8 and 1 mole per mole of TiCl₃present in the reduced solid is used.

The solid which has been treated with the complexing agent canoptionally be separated from the treatment medium by decantation orfiltration and washed with an inert diluent.

The treated solid generally has a physical form similar to that of thereduced solid, and a similar specific surface are. As for its chemicalconstitution, it contains, not only beta-TiCl₃ and the aluminumcompound, but also the complexing agent. The catalytic properties ofthis reacted solid, like those of the reduced solid, are not good.

The treated solid is then contacted with TiCl₄ in the pesence of thesilica treated with the aromatic ester previously described under theconditions described in British Pat. No. 1,391,067 for contactingtreated solid with TiCl₄. The weight percent of the treated silica inthe final catalytic complex can be in the range of about 90 to about 10,preferably about 60 to about 40. Preferably, the treated silica is mixedwith the treated solid prior to the contact with the TiCl₄. Contact withthe TiCl₄ can be accomplished either using undiluted TiCl₄ or in thepresence of an inert diluent. In the latter case the concentration ofthe TiCl₄ is preferably greater than 15% by volume, e.g., between 30 and40%. There may optionally be present also a certain amount of addedcomplexing agent, or of complexing agent remaining from the precedingoperation.

The reaction of the treated solid and treated silica with the TiCl₄ ispreferably effected at a temperature between -30° and +100° C., e.g.,between 40° and 80° C. Particularly good results are obtained when thetemperature is between 60° and 70° C. The reaction time is preferablybetween 30 minutes and 4 hours, e.g., between 1 and 3 hours. In thecourse of the reaction whereby the catalytic complex is formed, thetreated solid can be kept in suspension by moderate agitation. Theseparation of the catalytic complex from its reaction medium can beeffected by filtration or decantation and the complex can then be washedwith diluent to eliminate the residual TiCl₄ and also the by-products othe reaction. The resulting complex can be ground to suitable size, forexample, in the range of about 1 to about 25 microns, preferably about 1to about 5 microns.

The catalytic complexes prepared as described above can be used forpolymerizing olefins and enable highly crystalline polymers to beobtained. They can be used together with an activator comprising anorgano compound of a metal of Group Ia, IIa or IIIb of the PeriodicClassification, and preferably comprise an organo compound of aluminumof the formula AlR"'_(m) X'_(3-m) where R"' is a hydrocarbon radicalcontaining from 1 to 18 carbon atoms, X' is a halogen, and m is anynumber greater than 0 but not greater than 3. This organo compound ofaluminum (if used) can be identical with or different from the aluminumcompound of the same general type used as a reducing agent in thepreparation of the catalytic complex. Particularly good results areobtained with diethylaluminum chloride, which permits very high activityand stereospecificity to be attained by the catalytic system.

The catalytic systems described above can be used for the polymerizationof olefins whose molecule contains from 2 to 18, preferably 2 to 6carbon atoms, e.g., ethylene, propylene, butene-1, pentene-1, themethylbutenes-1, hexene-1, 3- and 4-methyl-pentenes-1, andvinylcyclohexane. They are particularly valuable in the polymerizationof propylene, butene-1, and 4-methyl-pentene-1 to give highly isotacticcrystalline polymers. They can also be used for the copolymerization ofthese olefins with one another and/or with diolefins containing from 4to 18 carbon atoms. The diolefins are preferably non-conjugatedaliphatic diolefins, e.g., hexadiene-1,4; non-conjugated monocyclicdiolefins, e.g., 4-vinylcyclohexene; alicyclic diolefins having anendocyclic bridge, e.g., dicyclopentadiene, or methylene- orethylidene-norbornene; and conjugated aliphatic diolefins, e.g.,butadiene or isoprene.

They can also be used for the production of so-called block copolymers,from mono-olefins and diolefins. These block copolymers comprise seriesof chain segments of various lengths, each segment consisting of ahomopolymer of a mono-olefin or of a random copolymer of an olefin andat least one comonomer; the (or each) comonomer can be a mono-olefin ordiolefin.

The process of the invention is particularly suitable for the productionof propylene homopolymers and of propylene copolymers containing atleast 50% (preferably 75%) by weight propylene.

The polymerization can be effected by any applicable process. Thus themonomer(s) can be dissolved or suspended in a hydrocarbon solvent ordiluent which preferably comprises one or more aliphatic orcycloaliphatic hydrocarbons, e.g., butane, pentane, hexane, heptane,cyclohexane, methylcyclohexane, or a mixture of two or more thereof. Thepolymerization can also be effected in the monomer or one of themonomers, assuming that this can be kept in the liquid state, or furtherin the gaseous phase.

The polymerization temperature can be between 20° and 200° C., and ispreferably when operating in suspension between 50° and 80° C. Thepressure can be between atmospheric pressure and 50 atmospheres, and itis preferably between 10 and 25 atmospheres, although the pressure isnaturally dependent on the temperature applied.

The polymerization can be effected continuously or batchwise.

The preparation of block copolymers can also be effected by anyapplicable process. It is preferred to employ a two-stage processconsisting in first polymerizing an olefin, e.g., propylene, asdescribed previously for homopolymerization, and then polymerizinganother mono-olefin and/or a diolefin, e.g., ethylene, in the presenceof the still active homopolymer chain. This second polymerization can beeffected after the monomer which has not reacted in the first stage hasbeen completely or partially removed.

The organometallic compound and the catalytic complex can be added tothe polymerization medium separately. It is also possible to bring theminto contact, suitably at a temperature between -40° and 80° C., for acertain period (e.g., up to 2 hours) before they are introduced into thepolymerization reactor.

The total amount of organometallic compound used is not critical; it canbe greater than 0.1 millimole per liter of diluent, of liquid monomer,or of reactor volume, and preferably it is greater than 1 millimole perliter.

The amount of catalytic complex used can suitably be determined inaccordance with its content of TiCl₃. It is preferably selected so thatthe concentration of the complex of the polymerization medium is higherthan 0.01 millimole of TiCl₃ per liter of diluent, of liquid monomer, orof reactor volume, and most preferably greater than 0.2 millimole perliter.

The ratio of the organometallic compound (the activator) to thecatalytic complex is also not critical. This ratio is preferablyselected so that the molar ratio of organometallic compound to TiCl₃present in the complex will be between 0.5 and 10, and most preferablybetween 1 and 8. Particularly good results are obtained when the molarratio is between 2 and 5.

The following examples illustrate the invention and are not intended tolimit the invention, but rather, are presented for purposes ofillustration. Example I illustrates a procedure for obtaining the novelcatalyst complex of this invention; and Example II illustrates the useof this catalyst in polymerizing propylene.

EXAMPLE I

To a solution of 15 milliliters of TiCl₄ in 60 milliliters of n-heptene,which had been cooled to 0° C., there was added 88 milliliters of a 25weight percent solution of diethylaluminum chloride in heptane dropwiseover a period of 4 hours with stirring. The mixture was warmed to 65° C.over 1 hour and held at that temperature for 1 hour. The resultantreduced solid was washed with n-heptane, filtered and dried. To 5.5grams of this solid there was added 60 milliliters of n-heptane and themixture was heated to 35° C. To the resulting mixture there was addednine milliliters of diisoamyl ether complexing agent, followed bystirring for 1 hour. The resultant treated solid was washed withn-heptane, filtered and dried.

Twenty grams of silica, having a surface area of about 600 square metersper gram and an average mesh size of 200, was calcined in hydrogen atatmospheric pressure and at a temperature of 700° C. for 3.5 hours. To17.6 grams of this material there was added 60 milliliters of n-heptaneand 9 milliliters of ethyl benzoate. The resulting mixture was stirredfor two hours at reflux (104° C.). The resultant treated silica waswashed with n-heptane, filtered and dried in vacuum.

To a mixture containing 60 milliliters of heptane and 5.5 grams of thetreated solid obtained above there was added 5.2 grams of the treatedsilica and this was heated to 65° C. There was then added thereto asolution of 12 milliliters of TiCl₄ in 18 milliliters of n-heptane. Theresulting material was heated at 65° C. for 2 hours, filtered and driedunder vacuum to obtain a novel catalyst complex. This complex was groundin a jar mill to obtain particles having a mean particle size in therange of about 1 to about 25 microns.

EXAMPLE II

To an autoclave containing 470 milliliters of n-heptane there was added0.8 gram of the catalyst complex prepared in Example I, transfer beingaccomplished by syringe with 30 milliliters of n-heptane. To theautoclave there was also added 7.2 milliliters of a 25 weight percentsolution of diethylaluminum chloride in heptane by syringe. Theautoclave was heated to 55° C. and the contents stirred at 700 RPM.Propylene was introduced into the autoclave at 30 seconds per squareinch gauge (210 kPa) and maintained at this pressure for the reactionperiod of 3.5 hours. The reactor contents were cooled and depressurizedat atmospheric pressure and the catalyst was deactivated with 100milliliters of isopropyl alcohol. The resulting polymer was stirredovernight in isopropyl alcohol, filtered and dried overnight in a vacuumoven. The tacticity of the polymer was determined by extraction inboiling n-heptane, using a Jacketed Soxlet Extractor, followed byovernight drying in a vacuum oven. The weight percent of polymerinsoluble in n-heptane is the isotactic index of the polymer.

An additional series of runs were made as in Example II but wherein thesilica treated with ethyl benzoate in the catalyst was replaced with (1)untreated silica, (2) silica treated with triethylaluminum or (3) silicatreated with CCl₄. Still another run was carried out wherein a catalystwas prepared and was used to polymerize propylene using the identicalprocedures described in Example 1 of British Pat. No. 1,391,067 startingat line 51 on page 7.

In the case wherein untreated silica was used, it was heated in air at500° C. for 3 hours. When the silica was treated with triethylaluminumor carbon tetrachloride the following procedures were used. Beforetreating with triethylaluminum, the silica was also heated in air at500° C. for 3.5 hours. Then 20 grams of the silica so heated wasrefluxed in 60 milliliters of n-heptane and nine milliliters of a 25weight percent solution of triethylaluminum in heptane. For treatmentwith carbon tetrachloride, the silica was treated with hydrogen at 500°C. for 3.5 hours. The temperature was then reduced to 300° C. and 15milliliters of carbon tetrachloride was passed over the silica bybubbling nitrogen through the carbon tetrachloride. The results obtainedare set forth in Table I.

                  TABLE I                                                         ______________________________________                                                          Grams Polypropylene                                                                          Weight Percent                                                 Produced Per Total                                                                           Polypropylene                                Run               Grams of Titanium                                                                            Insoluble In                                 No.  Catalyst Used                                                                              In Catalyst    Hot n-Heptane                                ______________________________________                                        I    British Patent                                                                             1557           97                                                No. 1,391,067                                                            II   Containing Sil-                                                                            848            97                                                ica Treated with                                                              Ethyl Benzoate                                                                (Example I)                                                              III  Containing Sil-                                                                            1755           69                                                ica Treated with                                                              Triethylaluminum                                                         IV   Containing Sil-                                                                            941            64                                                ica treated with                                                              CCl.sub.4                                                                V    Containing Un-                                                                             616            95                                                treated Silica                                                           ______________________________________                                    

The above data show that when the novel catalyst of this invention wasused in polymerizing propylene, the activity of the catalyst wasreduced, as desired, over the catalyst of British Pat. No. 1,391,067,but the isotacticity of the propylene polymer was unchanged. Run No. Vshows that when untreated silica was present in the catalyst systemproductivity was severely reduced. That the choice of material used totreat the silica is critical is also apparent from Runs Nos. III and IVwherein the isotacticity of the polymer was extremely poor. It shouldalso be noted that even though the activity of catalyst II is reducedcompared to that obtained from catalyst I, it is not reduced to thelevel expected from just a physical mixture, i.e., about 780. This valuewas expected because half the amount of titanium complex was used in IIcompared to I. Thus, the use of ethyl benzoate treated silica with thetitanium complex results in a more effective use of titanium. This isespecially evident when comparing the results from catalysts II and V.

A comparison was made of the particle size distribution of thepolypropylene obtained in Runs Nos. I and II of Table I. The results areset forth below in Table II.

                  TABLE II                                                        ______________________________________                                        Percent Polymer                                                                              Catalyst   Catalyst                                            Retained On    Of Run No. I                                                                             Of Run No. II                                       ______________________________________                                        80 Micron Sieve                                                                              88.8       55.7                                                40 Micron Sieve                                                                              8.1        20.6                                                20 Micron Sieve                                                                              1.6        12.3                                                Not Retained On                                                                              1.5        11.5                                                20 Micron Sieve                                                               ______________________________________                                    

The data in Table II show that the particle size of the polymer madeusing the catalyst of this invention is generally smaller than that madeusing the catalyst of British Pat. No. 1,391,067.

Although the invention has been described in considerable detail withparticular reference to certain preferred embodiments thereof,variations and modifications can be effected within the spirit and scopeof the invention as described hereinabove, and as defined in theappended claims.

We claim:
 1. A process for the polymerization of olefins which comprisescontacting said olefin at elevated temperatures and elevated pressureswith an activator and a solid, particulate, catalyst complex prepared bya process comprising reducing TiCl₄, containing the resultant reducedsolid with a complexing agent to obtain a treated solid and contactingthe treated solid with TiCl₄ in the presence of silica which has beentreated with an aromatic ester.
 2. A process as defined in claim 1wherein said aromatic ester is selected from the group consisting ofthose having the following formulas: ##STR2## wherein each Y is a memberselected from the group consisting of alkyl radicals having from aboutone to about eight carbon atoms and alkenyl radicals having from abouttwo to about eight carbon atoms, each X is a member selected from thegroup consisting of hydrogen, halogen radicals, alkoxy radicals havingfrom about one to about eight carbon atoms, alkyl radicals having fromabout one to about eight carbon atoms and alkenyl radicals having fromabout two to about eight carbon atoms, and x has a value of one or two.3. A process as defined in claim 1 wherein said aromatic ester is ethylbenzoate.
 4. A process as defined in claim 1 wherein said silica has amean particle size in the range of about 1 to about 100 microns.
 5. Aprocess as defined in claim 1 wherein said silica has a mean particlesize in the range of about 1 to about 25 microns.
 6. A process asdefined in claim 2 wherein said silica has a mean particle size in therange of about 1 to about 100 microns.
 7. A process as defined in claim2 wherein said silica has a mean particle size in the range of about 1to about 25 microns.
 8. A process as defined in claim 3 wherein saidsilica has a mean particle size in the range of about 1 to about 100microns.
 9. A process as defined in claim 3 wherein said silica has amean particle size in the range of about 1 to about 25 microns.
 10. Aprocess as defined in claim 1 wherein said silica is calcined at atemperature in the range of about 350° to about 700° C. for about one toabout five hours prior to being treated with said aromatic ester.
 11. Aprocess as defined in claim 1 wherein said silica is calcined at atemperature in the range of about 400° to about 500° C. for about two toabout three hours prior to being treated with said aromatic ester.
 12. Aprocess as defined in claim 2 wherein said silica is calcined at atemperature in the range of about 350° to about 700° C. for about one toabout five hours prior to being treated with said aromatic ester.
 13. Aprocess as defined in claim 2 wherein said silica is calcined at atemperature in the range of about 400° to about 500° C., for about twoto about three hours prior to being treated with said aromatic ester.14. A process as defined in claim 3 wherein said silica is calcined at atemperature in the range of about 350° to about 700° C. for about one toabout five hours prior to being treated with said aromatic ester.
 15. Aprocess as defined in claim 3 wherein said silica is calcined at atemperature in the range of about 400° to about 500° C. for about two toabout three hours prior to being treated with said aromatic ester.
 16. Aprocess as defined in claim 1 wherein said silica is treated with saidaromatic ester by introducing them into a hydrocarbon solvent, the molarratio of aromatic ester to silica being in the range of about 1:10 toabout 1:1, and heating the resultant slurry to a temperature in therange of about 70° to about 300° C. for about one to about ten hours.17. A process as defined in claim 1 wherein said silica is treated withsaid aromatic ester by introducing them into a hydrocarbon solvent, themolar ratio of aromatic ester to silica being in the range of about 1:8to about 1:2, and heating the resultant slurry to a temperature in therange of about 100° to about 200° C. for about two to about five hours.18. A process as defined in claim 2 wherein said silica is treated withsaid aromatic ester by introducing them into a hydrocarbon solvent, themolar ratio of aromatic ester to silica being in the range of about 1:10to about 1:1, and heating the resultant slurry to a temperature in therange of about 70° to about 300° C. for about one to about ten hours.19. A process as defined in claim 2 wherein said silica is treated withsaid aromatic ester by introducing them into a hydrocarbon solvent, themolar ratio of aromatic ester to silica being in the range of about 1:8to about 1:2, and heating the resultant slurry to a temperature in therange of about 100° to about 200° C. for about two to about five hours.20. A process as defined in claim 3 wherein said silica is treated withsaid aromatic ester by introducing them into a hydrocarbon solvent, themolar ratio of aromatic ester to silica being in the range of about 1:10to about 1:1, and heating the resultant slurry to a temperature in therange of about 70° to about 300° C. for about one to about ten hours.21. A process as defined in claim 3 wherein said silica is treated withsaid aromatic ester by introducing them into a hydrocarbon solvent, themolar ratio of aromatic ester to silica being in the range of about 1:8to about 1:2, and heating the resultant slurry to a temperature in therange of about 100° to about 200° C. for about two to about five hours.22. A process as defined in claim 1 wherein said TiCl₄ is reduced to asolid product based on TiCl₃ by means of treatment with a reducing agentof the formula AlR_(n) X_(3-n), wherein R is a hydrocarbon radicalcontaining from about 1 to about 18 carbon atoms, X is halogen and n isan integer greater than 0 but no greater than 3, said treatment beingconducted in an inert medium.
 23. A process as defined in claim 2wherein said TiCl₄ is reduced to a solid product based on TiCl₃ by meansof treatment with a reducing agent of the formula AlR_(n) X_(3-n),wherein R is a hydrocarbon radical containing from about 1 to about 18carbon atoms, X a halogen and n is an integer greater than 0 but nogreater than 3, said treatment being conducted in an inert medium.
 24. Aprocess as defined in claim 3 wherein said TiCl₄ is reduced to a solidproduct based on TiCl₃ by means of treatment with a reducing agent ofthe formula AlR_(n) X_(3-n), wherein R is a hydrocarbon radicalcontaining from about 1 to about 18 carbon atoms, X is halogen and n isan integer greater than 0 but no greater than 3, said treatment beingconducted in an inert medium.
 25. A process as defined in claim 1wherein said complexing agent is an organic compound containing groupscapable of donating one or more pairs of electrons selected from thegroup consisting of ethers, thioethers, thiols, phosphines, stibines,arsines, amines, amides, ketones and esters, said treatment beingconducted in an inert diluent.
 26. A process as defined in claim 2wherein said complexing agent is an organic compound containing groupscapable of donating one or more pairs of electrons selected from thegroup consisting of ethers, thioethers, thiols, phosphines, stibines,arsines, amines, amides, ketones and esters, said treatment beingconducted in an inert diluent.
 27. A process as defined in claim 3wherein said complexing agent is an organic compound containing groupscapable of donating one or more pairs of electrons selected from thegroup consisting of ethers, thioethers, thiols, phosphines, stibines,arsines, amines, amides, ketones and esters, said treatment beingconducted in an inert diluent.
 28. A process as defined in claim 1wherein said complexing agent is selected from the group consisting ofthose having the formulas R'--O--R", R'--S--R", R'--N--R" and R'--S--H,wherein R' and R" are each a hydrocarbon radical containing from 1 to 15carbon atoms.
 29. A process as defined in claim 2 wherein saidcomplexing agent is selected from the group consisting of those havingthe formulas R'--O--R", R'--S--R", R'--N--R" and R'--S--H, wherein R'and R" are each a hydrocarbon radical containing from 1 to 15 carbonatoms.
 30. A process as defined in claim 3 wherein said complexing agentis selected from the group consisting of those having the formulasR'--O--R", R'--S--R", R'--N--R" and R'--S--H, wherein R' and R" are eacha hydrocarbon radical containing from 1 to 15 carbon atoms.
 31. Aprocess as defined in claim 1 wherein the weight percent of the treatedsilica in the catalytic complex is in the range of about 90 to about 10.32. A process as defined in claim 1 wherein the weight percent of thetreated silica in the catalytic complex is in the range of about 60 toabout
 40. 33. A process as defined in claim 2 wherein the weight percentof the treated silica in the catalytic complex is in the range of about90 to about
 10. 34. A process as defined in claim 2 wherein the weightpercent of the treated silica in the catalytic complex is in the rangeof about 60 to about
 40. 35. A process as defined in claim 3 wherein theweight percent of the treated silica in the catalytic complex is in therange of about 90 to about
 10. 36. A process as defined in claim 3wherein the weight percent of the treated silica in the catalyticcomplex is in the range of about 60 to about
 40. 37. A process asdefined in claim 1 wherein said activator has the formula AlR"'_(m)X'_(3-m) wherein R"' is a hydrocarbon radical containing from 1 to 18carbon atoms, X' is halogen and m is a number greater than 0 but nogreater than
 3. 38. A process as defined in claim 2 wherein saidactivator has the formula AlR"'_(m) X'_(3-m) wherein R"' is ahydrocarbon radical containing from 1 to 18 carbon atoms, X' is halogenand m is a number greater than 0 but no greater than
 3. 39. A process asdefined in claim 3 wherein said activator has the formula AlR"'_(m)X'_(3-m) wherein R"' is a hydrocarbon radical containing from 1 to 18carbon atoms, X' is halogen and m is a number greater than 0 but nogreater than 3.